Systems and methods for immersion-cooled datacenters

ABSTRACT

A thermal management system for cooling electronic devices includes an immersion cooling system, a vapor buffer tank, and a liquid buffer tank. The immersion cooling system includes an immersion tank defining an immersion chamber, a working fluid in the immersion chamber, and a condenser. A liquid portion of the working fluid defines an immersion bath in the immersion chamber and a vapor portion defines a headspace above the immersion bath in the immersion chamber. The condenser condenses the vapor portion of the working fluid to the liquid portion of the working fluid. The vapor buffer tank is in fluid communication with the headspace, and a vapor valve selectively allows fluid communication between the vapor buffer tank and the headspace. The liquid buffer tank is in fluid communication with the immersion chamber, and a liquid valve selectively allows fluid communication between the liquid buffer tank and the immersion chamber.

BACKGROUND Background and Relevant Art

Computing devices can generate a large amount of heat during use. Thecomputing components can be susceptible to damage from the heat andcommonly require cooling systems to maintain the component temperaturesin a safe range during heavy processing or usage loads. Liquid coolingcan effectively cool components as liquid working fluids have morethermal mass than air or gas cooling. The liquid working fluid can bemaintained at a lower temperature by allowing vaporized fluid to riseout of the liquid. The vapor in the cooling liquid can adversely affectthe cooling performance of the working fluid. The vapor can be condensedand returned to the immersion tank.

BRIEF SUMMARY

In some embodiments, a thermal management system for cooling electronicdevices includes an immersion cooling system, a vapor buffer tank, and aliquid buffer tank. The immersion cooling system includes an immersiontank, a working fluid, and a condenser. The immersion tank defines animmersion chamber. The working fluid is positioned in the immersionchamber, with a liquid portion of the working fluid defining animmersion bath in the immersion chamber and a vapor portion of theworking fluid defining a headspace above the immersion bath in theimmersion chamber. The condenser is positioned in fluid communicationwith the headspace to condense the vapor portion of the working fluid tothe liquid portion of the working fluid. The immersion cooling system isin fluid communication with the vapor buffer tank and the liquid buffertank. The vapor buffer tank is in fluid communication with the headspaceof the immersion chamber, and a vapor valve is positioned between thevapor buffer tank and the headspace to selectively allow fluidcommunication between the vapor buffer tank and the headspace. Theliquid buffer tank is in fluid communication with the immersion chamber,and a liquid valve is positioned between the liquid buffer tank and theimmersion chamber to selectively allow fluid communication between theliquid buffer tank and the immersion chamber.

In some embodiments, a thermal management system for cooling electronicdevices includes a first immersion cooling system, a second immersioncooling system, a vapor buffer tank, and a liquid buffer tank. Eachimmersion cooling system includes an immersion tank, a working fluid,and a condenser. The immersion tank defines an immersion chamber. Theworking fluid is positioned in the immersion chamber, with a liquidportion of the working fluid defining an immersion bath in the immersionchamber and a vapor portion of the working fluid defining a headspaceabove the immersion bath in the immersion chamber. The condenser ispositioned in fluid communication with the headspace to condense thevapor portion of the working fluid to the liquid portion of the workingfluid. The immersion cooling system is in fluid communication with thevapor buffer tank and the liquid buffer tank. The vapor buffer tank isin fluid communication with the headspace of the immersion chamber ofthe first immersion cooling system, and a first vapor valve ispositioned between the vapor buffer tank and the headspace toselectively allow fluid communication between the vapor buffer tank andthe headspace. The vapor buffer tank is in fluid communication with theheadspace of the immersion chamber of the second immersion coolingsystem, and a second vapor valve is positioned between the vapor buffertank and the headspace to selectively allow fluid communication betweenthe vapor buffer tank and the headspace. The liquid buffer tank is influid communication with the immersion chamber of the first immersioncooling system, and a first liquid valve is positioned between theliquid buffer tank and the immersion chamber to selectively allow fluidcommunication between the liquid buffer tank and the immersion chamber.The liquid buffer tank is in fluid communication with the immersionchamber of the second immersion cooling system, and a second liquidvalve is positioned between the liquid buffer tank and the immersionchamber to selectively allow fluid communication between the liquidbuffer tank and the immersion chamber.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

Additional features and advantages will be set forth in the descriptionwhich follows, and in part will be obvious from the description, or maybe learned by the practice of the teachings herein. Features andadvantages of the disclosure may be realized and obtained by means ofthe instruments and combinations particularly pointed out in theappended claims. Features of the present disclosure will become morefully apparent from the following description and appended claims or maybe learned by the practice of the disclosure as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otherfeatures of the disclosure can be obtained, a more particulardescription will be rendered by reference to specific embodimentsthereof which are illustrated in the appended drawings. For betterunderstanding, the like elements have been designated by like referencenumbers throughout the various accompanying figures. While some of thedrawings may be schematic or exaggerated representations of concepts, atleast some of the drawings may be drawn to scale. Understanding that thedrawings depict some example embodiments, the embodiments will bedescribed and explained with additional specificity and detail throughthe use of the accompanying drawings in which:

FIG. 1 is a side schematic representation of an immersion coolingsystem, according to at least one embodiment of the present disclosure;

FIG. 2 is a side schematic representation of an immersion cooling systemwith an external condenser, according to at least one embodiment of thepresent disclosure;

FIG. 3 is a schematic cross-sectional view of a two-phase immersioncooling system with buffer tanks, according to at least one embodimentof the present disclosure;

FIG. 4 is a schematic cross-sectional view of a two-phase immersioncooling system with recirculating buffer tanks, according to at leastone embodiment of the present disclosure;

FIG. 5 is a flowchart illustrating a method of working fluid controls ina two-phase immersion cooling system, according to at least oneembodiment of the present disclosure; and

FIG. 6 is a schematic cross-sectional view of parallel two-phaseimmersion cooling systems with buffer tanks, according to at least oneembodiment of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates generally to systems and methods forthermal management of electronic devices or other heat-generatingcomponents. Immersion chambers surround the heat-generating componentsin a liquid working fluid, which conducts heat from the heat-generatingcomponents to cool the heat-generating components. As the working fluidabsorbs heat from the heat-generating components, the temperature of theworking fluid increases. In some embodiments, the working fluidvaporizes, introducing vapor into the liquid of the working fluid.

In large-scale computing centers, such as cloud-computing centers, dataprocessing centers, data storage centers, or other computing facilities,immersion cooling systems provide an efficient method of thermalmanagement for many computing components under a variety of operatingloads. In some embodiments, an immersion cooling system includes aworking fluid in an immersion tank and a condenser to extract heat fromthe vapor of the working fluid. The condenser then condenses the vaporphase of the working fluid into a liquid phase and returns the liquidworking fluid to the immersion chamber of the immersion tank. In someembodiments, the liquid working fluid absorbs heat from theheat-generating components, and one or more fluid conduits direct thehot liquid working fluid outside of the immersion chamber to a radiatoror region of lower temperature to cool the liquid working fluid.

Whether the immersion cooling system is a two-phase cooling system(wherein the working fluid vaporizes and condenses in a cycle) or aone-phase cooling system (wherein the working fluid remains in a singlephase in a cycle), the heat transported from the heat-generatingcomponents outside of the immersion chamber is further exchanged with anambient fluid to exhaust the heat from the system. An ambient liquid hasa greater rate of convective transfer compared to an ambient gas, andtherefore an immersion cooling system submerged in an ambient liquid mayexhaust heat from the immersion cooling system more efficiently and/orwithout active cooling such as fans or pumps to move the ambient fluidover the immersion cooling system heat exchanger or heat-dispersingelements. In at least one embodiment, an immersion cooling system issubmerged underwater, and heat is removed from the heat-generatingcomponents by the working fluid before the heat is transferred from theworking fluid to the ambient water outside of the immersion coolingsystem.

A conventional immersion cooling system 100, shown in FIG. 1, includesan immersion tank 102 containing an immersion chamber 104 and acondenser 106 in the immersion chamber 104. The immersion chamber 104contains a working fluid that has a liquid working fluid 108 and a vaporworking fluid 110 portion. The liquid working fluid 108 creates animmersion bath 112 in which a plurality of heat-generating components114 are positioned to heat the liquid working fluid 108 on supports 116.

Referring now to FIG. 2, an immersion cooling system 200 according tothe present disclosure includes an immersion tank 202 defining animmersion chamber 204 with a working fluid positioned therein. Theworking fluid transitions between a liquid working fluid 208 phase and avapor working fluid 210 phase to remove heat from hot or heat-generatingcomponents 214 in the immersion chamber 204. The liquid working fluid208 more efficiency receives heat from the heat-generating components214 and, upon transition to the vapor working fluid 210, the vaporworking fluid 210 can be removed from the immersion tank 202, cooled andcondensed by the condenser 206 to extract the heat from the workingfluid, and the liquid working fluid 208 can be returned to the liquidimmersion bath 212.

In some embodiments, the immersion bath 212 of the liquid working fluid208 has a plurality of heat-generating components 214 positioned in theliquid working fluid 208. The liquid working fluid 208 surrounds atleast a portion of the heat-generating components 214 and other objectsor parts attached to the heat-generating components 214. In someembodiments, the heat-generating components 214 are positioned in theliquid working fluid 208 on one or more supports 216. The support 216may support one or more heat-generating components 214 in the liquidworking fluid 208 and allow the working fluid to move around theheat-generating components 214. In some embodiments, the support 216 isthermally conductive to conduct heat from the heat-generating components214. The support(s) 216 may increase the effective surface area fromwhich the liquid working fluid 208 may remove heat through convectivecooling.

In some embodiments, the heat-generating components 214 includeelectronic or computing components or power supplies. In someembodiments, the heat-generating components 214 include computerdevices, such as individual personal computer or server blade computers.In some embodiments, one or more of the heat-generating components 214includes a heat sink or other device attached to the heat-generatingcomponent 214 to conduct away thermal energy and effectively increasethe surface area of the heat-generating component 214. In someembodiments, the heat-generating components 214 include an electricmotor.

As described, conversion of the liquid working fluid 208 to a vaporphase requires the input of thermal energy to overcome the latent heatof vaporization and may be an effective mechanism to increase thethermal capacity of the working fluid and remove heat from theheat-generating components. Because the vapor working fluid 210 rises inthe liquid working fluid 208, the vapor working fluid 210 can beextracted from the immersion chamber 204 in an upper vapor region of thechamber. A condenser 206 cools part of the vapor working fluid 210 backinto a liquid working fluid 208, removing thermal energy from the systemand reintroducing the working fluid into the immersion bath 212 of theliquid working fluid 208. The condenser 206 radiates or otherwise dumpsthe thermal energy from the working fluid into the ambient environmentor into a conduit to carry the thermal energy away from the coolingsystem.

In conventional immersion cooling systems, a liquid-cooled condenser isintegrated into the immersion tank and/or the chamber to efficiencyremove the thermal energy from the working fluid. In some embodimentsaccording to the present disclosure, an immersion cooling system 200 forthermal management of computing devices allows at least one immersiontank 202 and/or chamber 204 to be connected to and in fluidcommunication with an external condenser 206. In some embodiments, animmersion cooling system includes a vapor return line 218 that connectsthe immersion tank 202 to the condenser 206 and allows vapor workingfluid 210 to enter the condenser 206 from the immersion tank 202 and/orchamber 204 and a liquid return line 220 that connects the immersiontank 202 to the condenser 206 and allows liquid working fluid 208 toreturn to the immersion tank 202 and/or chamber 204.

The vapor return line 218 may be colder than the boiling temperature ofthe working fluid. In some embodiments, a portion of the vapor workingfluid condenses in the vapor return line 218. The vapor return line 218can, in some embodiments, be oriented at an angle such that the vaporreturn line 218 is non-perpendicular to the direction of gravity. Thecondensed working fluid can then drain either back to the immersion tank202 or forward to the condenser 206 depending on the direction of thevapor return line 218 slope. In some embodiments, the vapor return line218 includes a liquid collection line or valve, like a bleeder valve,that allows the collection and/or return of the condensed working fluidto the immersion tank 202 or condenser 206.

In some examples, an immersion cooling system 200 includes an air-cooledcondenser 206. An air-cooled condenser 206 may require fans or pumps toforce ambient air over one or more heat pipes or fins to conduct heatfrom the condenser to the air.

The working fluid has a boiling temperature below a critical temperatureat which the heat-generating components experience thermal damage. Forexample, the heat-generating components may be computing components thatexperience damage above 100° Celsius (C). In some embodiments, theboiling temperature of the working fluid is less than a criticaltemperature of the heat-generating components. In some embodiments, theboiling temperature of the working fluid is less about 90° C. In someembodiments, the boiling temperature of the working fluid is less about80° C. In some embodiments, the boiling temperature of the working fluidis less about 70° C. In some embodiments, the boiling temperature of theworking fluid is less about 60° C. In some embodiments, the boilingtemperature of the working fluid is at least about 35° C. In someembodiments, the working fluid includes water. In some embodiments, theworking fluid includes glycol. In some embodiments, the working fluidincludes a combination of water and glycol. In some embodiments, theworking fluid is an aqueous solution. In some embodiments, the workingfluid is an electronic liquid, such as FC-72 available from 3M, orsimilar non-conductive fluids. In some embodiments, the heat-generatingcomponents, supports, or other elements of the immersion cooling systempositioned in the working fluid have nucleation sites on a surfacethereof that promote the nucleation of vapor bubbles of the workingfluid at or below the boiling temperature of the working fluid. Similarto a cold plate or cold surface in a conventional condenser, thedroplets are the subcooled surface that allow condensation upon thedroplets themselves.

Referring now to FIG. 3, in some embodiments, an immersion coolingsystem 300 has an immersion chamber 304 that is hermetically sealed toprevent leakage of the working fluid to the surrounding environment. Insome embodiments, the immersion tank 302 is a housing for an informationtechnology (IT) Module 324 that is intended and/or designed tofail-in-place. A fail-in-place IT Module is intended and/or designed toremain in place for a predetermined period of time, whether the devicesin or connected to the IT Module continue to operate for the full periodor whether one or more devices fail during the period. The IT Module 324may be only intended and/or designed to be recovered at the end of thepredetermined period.

In some embodiments, the immersion chamber 304 is hermetically sealedand intended and/or designed to operate for a predetermined period.Repairs may be performed to the device(s) in or connected to the ITModule 324, but the hermetic seal on the immersion chamber 304 may slowthe repair or maintenance process. In the event of a condenser or othercooler failure, an immersion cooling system 300 according to the presentdisclosure may provide flow of working fluid into or out of theimmersion chamber 304 to prevent over-heating or over-pressurizing ofthe immersion chamber 304 and/or prevent liquid working fluid levelsfrom dropping below a predetermined level in the immersion chamber,which could otherwise result in damage to the heat-generating components314 contained therein.

In some embodiments, a condenser 306 cools the vapor working fluid inthe immersion chamber 304 using a circulating cooling fluid 326 fromcoils 328 to the condenser 306 to absorb and exhaust waste heat from theimmersion chamber 304. In some embodiments, a cold plate, a Peltiercooler, or other cooling surface cools the vapor working fluid in theimmersion chamber. The two-phase immersion cooling system absorbs heatfrom the heat-generating components 314 in the liquid working fluid 308,which boils the liquid working fluid 308. The vapor working fluid 310carries the heat to the condenser 306 or other cooling surface, whichcools the vapor working fluid 310.

In the event of a condenser 306 or cooling surface failure, the vaporworking fluid 310 may have no efficient heat sink in the headspace 330of the immersion chamber 304, limiting the condensation of the vaporworking fluid 310. A condenser failure, therefore, can result in areduction in cooling capacity through an increase in temperature in theimmersion chamber 304 and through a reduction in liquid working fluidlevel in the immersion chamber 304. Further, without condensation of thevapor working fluid 310, a hermetically sealed immersion chamber 304will experience an increase in internal pressure. An increase inpressure will produce an increase in the boiling temperature of theworking fluid, which may result in the liquid working fluid increasingin temperature above the normal boiling point and exposing theheat-generating components 314 to elevated temperatures, even when incontact with liquid working fluid 308.

Immersion cooling systems, according to some embodiments of the presentdisclosure, include at least one environmental sensor measure anenvironmental condition of the immersion chamber. Environmentalconditions in the immersion chamber may include a vapor temperature, aliquid temperature, an internal pressure, a liquid working fluid level,or other properties relating to the state of the working fluid in theimmersion chamber.

For example, an environmental sensor may be a temperature sensor 332positioned in the headspace 330 of the immersion chamber 304 to measurea vapor temperature of the immersion chamber 304. In some examples, anenvironmental sensor may be a temperature sensor 332 positioned in theimmersion bath 312 of the immersion chamber 304 to measure a liquidtemperature of the liquid working fluid 308 in the immersion chamber304. In some examples, an environmental sensor may be a pressure sensor334 positioned in the immersion chamber 304 to measure an internalpressure of the immersion chamber 304. While a pressure sensor at abottom of the immersion chamber may read differently than a pressuresensor 334 in the headspace of the immersion chamber 304, both willreport equal increases in the event of a pressure increase in theimmersion chamber 304.

In some examples, an environmental sensor may be a liquid level sensor336 positioned in the immersion chamber to measure a liquid workingfluid level of the immersion chamber. The liquid level sensor 336 may bea liquid contact switch positioned below the surface level of the liquidworking fluid 308. For example, when submerged in the liquid workingfluid 308, the liquid contact switch 336 may be closed, and, when theliquid working fluid level drops due to vaporization of the liquidworking fluid 308, the contact switch is exposed to the vapor workingfluid 310 above the liquid working fluid 308, opening the switch. Inother examples, the liquid level sensor 336 may be an optical sensorthat detects a light reflect and/or refracted by the liquid workingfluid 308. In some examples, the liquid level sensor 336 is a pressuresensor that measures a mass of the liquid working fluid 308 present inthe immersion chamber 304 above the liquid level sensor 336. In someexamples, the liquid level sensor 336 is a float sensor that measures aheight of the liquid level sensor 336.

In some embodiments, the immersion cooling system includes a pluralityof environmental sensors. For example, a vapor temperature sensor maydetect and increase in vapor working fluid temperature (and hence acondenser failure) before an appreciable increase in liquid workingfluid temperature is detected. In some embodiments, a liquid levelsensor measures changes in liquid level independently from temperaturechanges, in the event that vapor working fluid is vented from theimmersion chamber.

In the event of a condenser failure, the working fluid in the immersionchamber may continue to boil, increasing the temperature and pressure ofthe vapor working fluid in the headspace of the immersion chamber. Aportion of the vapor working fluid 310 may be safely vented from theheadspace 330 into a vapor buffer tank 338 to reduce the pressure in theheadspace 330. In some embodiments, reducing the pressure in theheadspace 330 also cools the remaining vapor working fluid 310 in theheadspace 330.

The vapor buffer tank 338 is connected to the immersion chamber 304through a vapor conduit 340. In some embodiments, the vapor conduit 340includes a valve 342 that allows flow of vapor working fluid from thehigh pressure in the immersion chamber to the vapor buffer tank. Thevapor working fluid 310 will flow to the region of lower pressure. Insome embodiments, the vapor conduit includes a vapor pump 344 to urge(e.g., pump) vapor working fluid 310 from the immersion chamber 304 intothe vapor buffer tank 338. A pump may allow the vapor buffer tank tocontinue increasing in pressure above the pressure of the immersionchamber. The vapor conduit is in fluid communication with the headspaceof the immersion chamber. In some embodiments, the vapor conduit 340 isconnected to a top surface of the immersion tank 302. In someembodiments, the vapor conduit 340 is connected to an upper portion of asidewall of the immersion tank 302 above the liquid working fluid level.

In some embodiments, the immersion cooling system 300 further includes aliquid buffer tank 346. The liquid buffer tank 346 is a separate tank influid communication with the immersion chamber 304 by a liquid conduit348. In some embodiments, the liquid conduit 348 includes a liquid valve350 that allows flow of liquid working fluid 308 between the liquidbuffer tank 346 and the immersion chamber 304. For example, if a levelof the liquid buffer tank 346 is higher than the liquid working fluidlevel in the immersion chamber 304, the liquid working fluid 308 willflow into the immersion chamber 304. In some embodiments, at least aportion of the liquid buffer tank 346 is positioned higher than theimmersion tank 302 of the immersion cooling system 300. In someembodiments, the bottom of the liquid buffer tank 346 is positionedhigher than the top of the immersion tank 302 of the immersion coolingsystem 300. In some embodiments, the bottom of the liquid buffer tank346 is positioned at or near the top of the heat-generating components314 in the immersion tank 302 of the immersion cooling system 300.

In some embodiments, the liquid conduit 348 includes a liquid pump 352to urge liquid working fluid 308 from the liquid buffer tank 346 to theimmersion chamber 304. A liquid pump 352 may allow the liquid buffertank 346 to continue delivering supplemental liquid working fluid 308 tothe immersion chamber 304, irrespective of the relative heights of theliquid levels in each tank.

In some embodiments, the valves and/or pumps of the vapor conduit 340and the liquid conduit 348 are controlled and/or actuated at the sametime. In some embodiments, the valves and/or pumps of the vapor conduit340 and the liquid conduit 348 are controlled and/or actuated based ondifferent environmental sensors or other sensors. For example, a vaporpump 342 may be actuated based on a measurement from a temperaturesensor 332 positioned in the headspace 330 to measure the vaportemperature, and the liquid pump 352 may be actuated based on ameasurement from a liquid level sensor 336.

In some embodiments, in addition to the environmental sensor(s)positioned in or on the immersion tank, an immersion cooling systemincludes one or more flow sensors positioned in or on the vapor conduitand/or the liquid conduit. The flow sensors can measure the rate and/ortotal amount of vapor working fluid and/or liquid working fluid thatmoves out of and/or into the immersion chamber. For example, a vaporflow rate sensor on the vapor conduit may measure the total vaporworking fluid vented from the immersion chamber, and a liquid flow ratesensor may measure the total amount of liquid working fluid introducedto the immersion chamber. In some embodiments, the mass of the liquidworking fluid introduced by the liquid pump or through the liquid valveis related to the measured mass of vapor released from the immersionchamber.

A liquid valve controller may be in electrical communication with theliquid valve and/or pump and with at least one sensor. The liquid valvecontroller receives measurements from the sensor to determine when toopen the liquid valve and/or actuate the liquid pump. It should beunderstood that the liquid valve controller, as used herein, selectivelycontrols the flow of liquid working fluid through the liquid conduit,irrespective of whether the liquid valve controller controls a valve,pump, or other mechanisms. A vapor valve controller may be in electricalcommunication with the vapor valve and/or pump and with at least onesensor. The vapor valve controller receives measurements from the sensorto determine when to open the vapor valve and/or actuate the vapor pump.It should be understood that the vapor valve controller, as used herein,selectively controls the flow of vapor working fluid through the vaporconduit, irrespective of whether the vapor valve controller controls avalve, pump, or other mechanisms.

The vapor buffer tank 338 allows the high pressure and/or hightemperature vapor working fluid 310 to exit the immersion chamber 304(without venting to atmosphere), which, in turn, allows the liquidworking fluid 308 in the immersion chamber 304 to boil at the expectedtemperature and maintain cooling for the heat-generating components 314,in the event of a condenser failure. If technicians are unable to repairor restart the condenser 306 in the immersion chamber 304 before theliquid working fluid level falls below a threshold level, the liquidbuffer tank 346 can provide supplemental liquid working fluid 308 intothe immersion chamber 304 to raise the liquid working fluid level andcool the immersion chamber 304.

Referring now to FIG. 4, in some embodiments, a vapor buffer tank 438may allow for at least a portion of the excess vapor working fluid 410to condense into a condensate 454. In some embodiments, the vapor buffertank 438 includes a condenser or other cooling surface. In someembodiments, the vapor buffer tank 438 is allowed to remain at ambienttemperature, which may be sufficient to condense the vapor working fluid410 to the condensate 454. The condensate 454 may be returned to theliquid buffer tank 446 by a return conduit 456. In some embodiments, areturn pump 458 is positioned in the return conduit 454 to urge thecondensate 454 through the return conduit 456 into the liquid buffertank 446. The condensate 454 may at least partially refill the liquidbuffer tank 446, allowing further supplemental liquid working fluid 408to be available, if needed, to maintain the liquid working fluid levelin the immersion chamber 404.

FIG. 5 is a flowchart illustrating a method 560 of thermal managementwith immersion cooling. In some embodiments, a method 560 of thermalmanagement according to the present disclosure includes at leastpartially surrounding heat-generating components with a liquid workingfluid in an immersion chamber to receive heat from the heat-generatingcomponent at 562. The method includes measuring at least the temperatureand/or pressure in the immersion chamber at 564. Upon the temperatureand/or pressure exceeding a threshold value, the method includes ventinga portion of the vapor working fluid from the immersion chamber to avapor buffer tank at 566, using any of the sensors, valves, or pumps asdescribed herein.

The threshold values may be set based on a percentage of thesteady-state operating conditions. In some embodiments, the thresholdvalue for the vapor temperature of the vapor working fluid in theheadspace may be 5% above the boiling temperature in Celsius. Forexample, if the boiling temperature is 60° C., the threshold value maybe 63° C. In some embodiments, the threshold value may be a nominalamount above the steady state operating condition, such as a 5 pound persquare inch (psi) increase in the pressure in the immersion chamber.

In some embodiments, the method includes venting the portion of thevapor working fluid from the immersion chamber before opening a liquidvalve and/or actuating a liquid pump to introduce supplemental liquidworking fluid to the immersion chamber at 570. The liquid valve may beopened and/or the liquid pump may be actuated at a predetermined timeinterval after the vapor working fluid is vented from the immersionchamber at 568. For example, an internal pressure of the immersionchamber will decrease upon venting the pressurized vapor working fluidfrom the headspace to the vapor buffer tank. In some embodiments, theimmersion cooling system may open the liquid valve and/or actuate theliquid pump after 5 seconds, 10 seconds, 15 second, 20 seconds, 30seconds, 1 minutes, or another predetermined time interval to allow theimmersion chamber to depressurize before introducing supplemental liquidworking fluid into the immersion chamber.

In some embodiments, the liquid valve may be opened and/or the liquidpump may be actuated after the vapor working fluid is vented based on aliquid level sensor measurement or a pressure measurement at 572. Insome embodiments, the liquid valve may be opened and/or the liquid pumpmay be actuated any time the liquid level falls below a threshold levelto maintain the liquid working fluid level at 574, such as in the eventof a leak from the immersion tank. In some embodiments, the liquid valvemay be opened and/or the liquid pump may be actuated only after vaporworking fluid is vented from the immersion chamber. At which point, theliquid valve may be opened and/or the liquid pump may be actuated if theliquid working fluid level falls below a threshold level to maintain theliquid working fluid level.

In a particular example, the pressure sensor may be in communicationwith the vapor valve controller and the liquid valve controller. When aninternal pressure of the immersion chamber exceeds a vent thresholdvalue, the vapor valve controller may open the vapor valve and/oractuate the vapor pump to vent the vapor working fluid from theimmersion chamber and lower the internal pressure in the immersionchamber. After the vapor is vented, and the pressure decreases below afill threshold value, the liquid valve controller may open the liquidvalve and/or actuate the liquid pump to introduce the supplementalliquid working fluid into the immersion chamber from the liquid buffertank. By only opening the liquid valve and/or actuating the liquid pumpafter the pressure has dropped, the supplemental liquid working fluidwill not experience the elevated internal pressure of the immersionchamber applying a force to the supplemental liquid working fluid thatresists the flow of the supplemental liquid working fluid into theimmersion chamber from the liquid buffer tank.

In some embodiments, in addition to the environmental sensor(s)positioned in or on the immersion tank, an immersion cooling systemincludes one or more flow sensors positioned in or on the vapor conduitand/or the liquid conduit. The flow sensors can measure the rate and/ortotal amount of vapor working fluid and/or liquid working fluid thatmoves out of and/or into the immersion chamber. For example, a flow rateof the vapor working fluid through the vapor conduit may be converted toa flow rate of the liquid working fluid through the liquid conduit basedon a relative density of the vapor phase to the liquid phase of theworking fluid to ensure the mass of working fluid in the immersionchamber remains substantially constant as vapor working fluid is ventedand supplemental liquid working fluid is introduced.

Optionally, the method includes condensing at least some of the ventedportion of the vapor working fluid in the vapor buffer tank to acondensate working fluid at 576 and returning the condensate workingfluid to the liquid buffer tank at 578. In some embodiments, the vaporbuffer tank may include a condenser or other cooling surface to assistcondensing the vapor working fluid. In some embodiments, at least someof the vapor working fluid will condense in the vapor buffer tank in theabsence of heat-generating components.

In some embodiments, such as that shown in FIG. 6, a vapor buffer tank638 and/or liquid buffer tank 646 are connected to a plurality of sealedIT modules 624. An immersion cooling system 600 can include a pluralityof sealed IT Modules 624 connected in parallel with a vapor buffer tank638 and/or liquid buffer tank 646. In some embodiments, each of theparallel IT Modules 624 has a vapor valve and/or vapor pump (such as thevapor conduit 340 described in relation to FIG. 3) positioned in or on avapor conduit to selectively connect the IT Module 624 to a vapor commonconduit 680 that combines vapor working fluid from more than one ITModule 624. In some embodiments, each of the parallel IT Modules 624 hasa dedicated vapor conduit that connects the individual IT Module 624 tothe vapor buffer tank 638.

In some embodiments, each of the parallel IT Modules 624 has a liquidvalve and/or liquid pump positioned in or on a liquid conduit (such asthe liquid conduit 348 described in relation to FIG. 3) to selectivelyconnect the IT Module 624 to a liquid common conduit 682 that providessupplemental liquid working fluid to more than one IT Module 624. Insome embodiments, each of the parallel IT Modules 624 has a dedicatedliquid conduit that connects the individual IT Module 624 to the liquidbuffer tank 646.

In the event of a failure of any of the condensers in each of the ITModules, the immersion cooling system 600 can vent vapor working fluidfrom the IT Module experiencing the failure to the vapor buffer tank638. The immersion cooling system can then direct supplemental workingfluid from the shared liquid buffer tank 646 to the IT Module 624needing it.

Industrial Applicability

The present disclosure relates generally to systems and methods forthermal management of electronic devices or other heat-generatingcomponents. Immersion chambers surround or partially surround theheat-generating components in a liquid working fluid, which conductsheat from the heat-generating components to cool the heat-generatingcomponents. As the working fluid absorbs heat from the heat-generatingcomponents, the temperature of the working fluid increases and theworking fluid may vaporize, introducing vapor into the liquid of theworking fluid. The vapor will rise due to buoyancy in the oppositedirection of gravity, accumulating in a headspace of the immersionchamber above the immersion bath of liquid working fluid.

An immersion cooling system according to the present disclosure includesan immersion chamber with a working fluid positioned therein. Theworking fluid transitions between a liquid phase and a vapor phase toremove heat from hot or heat-generating components in the chamber. Theliquid phase more efficiency receives heat from the components and, upontransition to the vapor phase, the working fluid can be cooled andcondensed to extract the heat from the working fluid before the workingfluid is returned to the liquid immersion bath at a lower temperature.

In some embodiments, the immersion bath of the liquid working fluid hasa plurality of heat-generating components positioned in the liquidworking fluid. The liquid working fluid surrounds the heat-generatingcomponents and other objects or parts attached to the heat-generatingcomponents. In some embodiments, the heat-generating components arepositioned in the liquid working fluid on one or more supports. Thesupport may support one or more heat-generating components in the liquidworking fluid and allow the working fluid to move around theheat-generating components. In some embodiments, the support isthermally conductive to conduct heat from the heat-generatingcomponents. The support(s) may increase the effective surface area fromwhich the working fluid may remove heat through convective cooling. Insome embodiments, one or more of the heat-generating components includesa heat sink or other device attached to the heat-generating component toconduct away thermal energy and effectively increase the surface area ofthe heat-generating component.

As described, conversion of the liquid working fluid to a vapor phaserequires the input of thermal energy to overcome the latent heat ofvaporization and may be an effective mechanism to increase the thermalcapacity of the working fluid and remove heat from the heat-generatingcomponents. Because the vapor rises in the liquid working fluid, thevapor phase of the working fluid accumulates in an upper vapor region ofthe chamber. Conventionally, a condenser cools part of the vapor of theworking fluid back into a liquid phase, removing thermal energy from thesystem and reintroducing the working fluid into the immersion bath ofthe liquid working fluid. The condenser radiates or otherwise dumps thethermal energy from the working fluid into the ambient environment orinto a conduit to carry the thermal energy away from the cooling system.

In some embodiments, the liquid working fluid receives heat in a coolingvolume of working fluid immediately surrounding the heat-generatingcomponents. The cooling volume is the region of the working fluid(including both liquid and vapor phases) that is immediately surroundingthe heat-generating components and is responsible for the convectivecooling of the heat-generating components. In some embodiments, thecooling volume is the volume of working fluid within 5 millimeters (mm)of the heat-generating components.

The working fluid has a boiling temperature below a critical temperatureat which the heat-generating components experience thermal damage. Forexample, the heat-generating components may be computing components thatexperience damage above 100° Celsius (C). In some embodiments, theboiling temperature of the working fluid is less than a criticaltemperature of the heat-generating components. In some embodiments, theboiling temperature of the working fluid is less about 90° C. In someembodiments, the boiling temperature of the working fluid is less about80° C. In some embodiments, the boiling temperature of the working fluidis less about 70° C. In some embodiments, the boiling temperature of theworking fluid is less about 60° C. In some embodiments, the boilingtemperature of the working fluid is at least about 35° C. In someembodiments, the working fluid includes water. In some embodiments, theworking fluid includes glycol. In some embodiments, the working fluidincludes a combination of water and glycol. In some embodiments, theworking fluid is an aqueous solution. In some embodiments, the workingfluid is an electronic liquid, such as FC-72 available from 3M, orsimilar non-conductive fluids. In some embodiments, the heat-generatingcomponents, supports, or other elements of the immersion cooling systempositioned in the working fluid have nucleation sites on a surfacethereof that promote the nucleation of vapor bubbles of the workingfluid at or below the boiling temperature of the working fluid. Similarto a cold plate or cold surface in a conventional condenser, thedroplets are the subcooled surface that allow condensation upon thedroplets themselves.

In some embodiments, the immersion chamber is hermetically sealed toprevent leakage of the working fluid to the surrounding environment. Insome embodiments, the immersion chamber is a housing for an informationtechnology (IT) Module that is intended and/or designed tofail-in-place. A fail-in-place IT Module is intended and/or designed toremain in place for a predetermined period of time, whether the devicesin or connected to the IT Module continue to operate for the full periodor whether one or more devices fail during the period. The IT Module isonly intended and/or designed to be recovered at the end of thepredetermined period.

In some embodiments, the immersion chamber is hermetically sealed andintended and/or designed to operate for a predetermined period. Repairsmay be performed to the device(s) in or connected to the IT Module, butthe hermetic seal on the immersion chamber may slow the repair ormaintenance process. In the event of a condenser or other coolerfailure, an immersion cooling system according to the present disclosuremay provide supplemental flow of working fluid into or out of theimmersion chamber to prevent over-heating or over-pressurizing of theimmersion chamber and/or prevent liquid working fluid levels fromdropping below a predetermined level in the immersion chamber.

In some embodiments, a condenser cools the vapor working fluid in theimmersion chamber using a circulating cooling fluid in the condenser toabsorb and exhaust waste heat from the immersion chamber. In someembodiments, a cold plate, a Peltier cooler, or other cooling surfacecools the vapor working fluid in the immersion chamber. The two-phaseimmersion cooling system absorbs heat from the heat-generatingcomponents in the liquid working fluid, which boils the liquid workingfluid. The vapor working fluid carries the heat to the condenser orother cooling surface, which cools the vapor working fluid.

In the event of a condenser or cooling surface failure, the vapor mayhave no efficient heat sink in the headspace of the immersion chamber,limiting the condensation of the vapor working fluid. A condenserfailure, therefore, can result in a reduction in cooling capacitythrough an increase in temperature in the immersion chamber and througha reduction in liquid working fluid level in the immersion chamber.Further, without condensation of the vapor working fluid, a hermeticallysealed immersion chamber will experience an increase in internalpressure. An increase in pressure will produce an increase in theboiling temperature of the working fluid, which may result in the liquidworking fluid increasing in temperature above the normal boiling pointand exposing the heat-generating components to elevated temperatures,even in the presence of liquid working fluid.

Immersion cooling systems, according to some embodiments of the presentdisclosure, include at least one environmental sensor measure anenvironmental condition of the immersion chamber. Environmentalconditions in the immersion chamber may include a vapor temperature, aliquid temperature, an internal pressure, a liquid working fluid level,or other properties relating to the state of the working fluid in theimmersion chamber.

For example, an environmental sensor may be a temperature sensorpositioned in the headspace of the immersion chamber to measure a vaportemperature of the immersion chamber. In some examples, an environmentalsensor may be a temperature sensor positioned in the immersion bath ofthe immersion chamber to measure a liquid temperature of the liquidworking fluid in the immersion chamber. In some examples, anenvironmental sensor may be a pressure sensor positioned in theimmersion chamber to measure an internal pressure of the immersionchamber. While a pressure sensor at a bottom of the immersion chambermay read differently than a pressure sensor in the headspace of theimmersion chamber, both will report equal increases in the event of apressure increase in the immersion chamber.

In some examples, an environmental sensor may be a liquid level sensorpositioned in the immersion chamber to measure a liquid working fluidlevel of the immersion chamber. The liquid level sensor may be a liquidcontact switch positioned below the surface level of the liquid workingfluid. For example, when submerged in the liquid working fluid, theliquid contact switch may be closed, and, when the liquid working fluidlevel drops due to vaporization of the liquid working fluid, the contactswitch is exposed to the vapor working fluid above the liquid workingfluid, opening the switch. In other examples, the liquid level sensormay be an optical sensor that detects a light reflect and/or refractedby the liquid working fluid. In some examples, the liquid level sensoris a pressure sensor that measures a mass of the liquid working fluidpresent in the immersion chamber above the liquid level sensor. In someexamples, the liquid level sensor is a float sensor that measures aheight of the liquid level sensor.

In some embodiments, the immersion cooling system includes a pluralityof environmental sensors. For example, a vapor temperature sensor maydetect and increase in vapor working fluid temperature (and hence acondenser failure) before an appreciable increase in liquid workingfluid temperature is detected. In some embodiments, a liquid levelsensor measures changes in liquid level independently from temperaturechanges, in the event that vapor working fluid is vented from theimmersion chamber.

In the event of a condenser failure, the working fluid in the immersionchamber may continue to boil, increasing the temperature and pressure ofthe vapor working fluid in the headspace of the immersion chamber. Aportion of the vapor working fluid may be safely vented from theheadspace into vapor buffer tank to reduce the pressure in theheadspace. In some embodiments, reducing the pressure in the headspacealso cools the remaining vapor working fluid in the headspace.

The vapor buffer tank is connected to the immersion chamber through avapor conduit. In some embodiments, the vapor conduit includes a valvethat allows flow of vapor working fluid from the high pressure in theimmersion chamber to the vapor buffer tank. The vapor working fluid willflow to the region of lower pressure. In some embodiments, the vaporconduit includes a pump to urge vapor working fluid from the immersionchamber into the vapor buffer tank. A pump may allow the vapor buffertank to continue increasing in pressure above the pressure of theimmersion chamber. The vapor conduit is in fluid communication with theheadspace of the immersion chamber. In some embodiments, the vaporconduit is connected to a top surface of the immersion tank. In someembodiments, the vapor conduit is connected to an upper portion of asidewall above the liquid working fluid level.

In some embodiments, the immersion cooling system further includes aliquid buffer tank. The liquid buffer tank is a separate tank in fluidcommunication with the immersion chamber by a liquid conduit. In someembodiments, the liquid conduit includes a valve that allows flow ofliquid working fluid between the liquid buffer tank and the immersionchamber. For example, if a level of the liquid buffer tank is higherthan the liquid working fluid level in the immersion chamber, the liquidworking fluid will flow into the immersion chamber. In some embodiments,at least a portion of the liquid buffer tank is positioned higher thanthe immersion tank of the immersion cooling system. In some embodiments,the bottom of the liquid buffer tank is positioned higher than the topof the immersion tank of the immersion cooling system. In someembodiments, the bottom of the liquid buffer tank is positioned at ornear the top of the heat-generating components in the immersion tank ofthe immersion cooling system.

In some embodiments, the liquid conduit includes a pump to urge liquidworking fluid from the liquid buffer tank to the immersion chamber. Apump may allow the liquid buffer tank to continue delivering extraliquid working fluid to the immersion chamber, irrespective of therelative heights of the liquid levels in each tank.

In some embodiments, the valves and/or pumps of the vapor conduit andthe liquid conduit are controlled and/or actuated at the same time. Insome embodiments, the valves and/or pumps of the vapor conduit and theliquid conduit are controlled and/or actuated based on differentenvironmental sensors or other sensors. For example, a vapor pump may beactuated based on a measurement from a temperature sensor positioned inthe headspace to measure the vapor temperature, and the liquid pump maybe actuated based on a measurement from a liquid level sensor.

In some embodiments, in addition to the environmental sensor(s)positioned in or on the immersion tank, an immersion cooling systemincludes one or more flow sensors positioned in or on the vapor conduitand/or the liquid conduit. The flow sensors can measure the rate and/ortotal amount of vapor working fluid and/or liquid working fluid thatmoves out of and/or into the immersion chamber. For example, a vaporflow rate sensor on the vapor conduit may measure the total vaporworking fluid vented from the immersion chamber, and a liquid flow ratesensor may measure the total amount of liquid working fluid introducedto the immersion chamber. In some embodiments, the mass of the liquidworking fluid introduced by the liquid pump or through the liquid valveis related to the measured mass of vapor released from the immersionchamber.

A liquid valve controller may be in electrical communication with theliquid valve and/or pump and with at least one sensor. The liquid valvecontroller receives measurements from the sensor to determine when toopen the liquid valve and/or actuate the liquid pump. It should beunderstood that the liquid valve controller, as used herein, selectivelycontrols the flow of liquid working fluid through the liquid conduit,irrespective of whether the liquid valve controller controls a valve,pump, or other mechanisms. A vapor valve controller may be in electricalcommunication with the vapor valve and/or pump and with at least onesensor. The vapor valve controller receives measurements from the sensorto determine when to open the vapor valve and/or actuate the vapor pump.It should be understood that the vapor valve controller, as used herein,selectively controls the flow of vapor working fluid through the vaporconduit, irrespective of whether the vapor valve controller controls avalve, pump, or other mechanisms.

The vapor buffer tank allows the high pressure and/or high temperaturevapor working fluid to exit the immersion chamber (without venting toatmosphere), which, in turn, allows the liquid working fluid in theimmersion chamber to boil at the expected temperature and maintaincooling for the heat-generating components, in the event of a condenserfailure. If technicians are unable to repair or restart the condenser inthe immersion chamber before the liquid working fluid level falls belowa threshold level, the liquid buffer tank can provide supplementalliquid working fluid into the immersion chamber to raise the liquidworking fluid level and cool the immersion chamber.

In some embodiments, the vapor buffer tank may allow for at least aportion of the excess vapor working fluid to condense into a condensate.In some embodiments, the vapor buffer tank includes a condenser or othercooling surface. In some embodiments, the vapor buffer tank is allowedto remain at ambient temperature, which may be sufficient to condensethe vapor working fluid to the condensate. The condensate may bereturned to the liquid buffer tank by a return conduit. In someembodiments, a return pump is positioned in the return conduit to urgethe condensate through the return conduit into the liquid buffer tank.The condensate may at least partially refill the liquid buffer tank,allowing further supplemental liquid working fluid to be available, ifneeded, to maintain the liquid working fluid level in the immersionchamber.

In some embodiments, a method of thermal management according to thepresent disclosure includes at least partially surroundingheat-generating components with a liquid working fluid in an immersionchamber to receive heat from the heat-generating component. The methodincludes measuring at least the temperature and/or pressure in theimmersion chamber. Upon the temperature and/or pressure exceeding athreshold value, the method includes venting a portion of the vaporworking fluid from the immersion chamber to a vapor buffer tank.

The threshold values may be set based on a percentage of thesteady-state operating conditions. In some embodiments, the thresholdvalue for the vapor temperature of the vapor working fluid in theheadspace may be 5% above the boiling temperature in Celsius. Forexample, if the boiling temperature is 60° C., the threshold value maybe 63° C. In some embodiments, the threshold value may be a nominalamount above the steady state operating condition, such as a 5 pound persquare inch (psi) increase in the pressure in the immersion chamber.

In some embodiments, the method includes venting the portion of thevapor working fluid from the immersion chamber before opening a liquidvalve and/or actuating a liquid pump to introduce supplemental liquidworking fluid to the immersion chamber. The liquid valve may be openedand/or the liquid pump may be actuated at a predetermined time intervalafter the vapor working fluid is vented from the immersion chamber. Forexample, an internal pressure of the immersion chamber will decreaseupon venting the pressurized vapor working fluid from the headspace tothe vapor buffer tank. In some embodiments, the immersion cooling systemmay open the liquid valve and/or actuate the liquid pump after 5seconds, 10 seconds, 15 second, 20 seconds, 30 seconds, 1 minutes, oranother predetermined time interval to allow the immersion chamber todepressurize before introducing supplemental liquid working fluid intothe immersion chamber.

In some embodiments, the liquid valve may be opened and/or the liquidpump may be actuated after the vapor working fluid is vented based on aliquid level sensor measurement or a pressure measurement. In someembodiments, the liquid valve may be opened and/or the liquid pump maybe actuated any time the liquid level falls below a threshold level tomaintain the liquid working fluid level, such as in the event of a leakfrom the immersion tank. In some embodiments, the liquid valve may beopened and/or the liquid pump may be actuated only after vapor workingfluid is vented from the immersion chamber. At which point, the liquidvalve may be opened and/or the liquid pump may be actuated if the liquidworking fluid level falls below a threshold level to maintain the liquidworking fluid level.

In a particular example, the pressure sensor may be in communicationwith the vapor valve controller and the liquid valve controller. When aninternal pressure of the immersion chamber exceeds a vent thresholdvalue, the vapor valve controller may open the vapor valve and/oractuate the vapor pump to vent the vapor working fluid from theimmersion chamber and lower the internal pressure in the immersionchamber. After the vapor is vented, and the pressure decreases below afill threshold value, the liquid valve controller may open the liquidvalve and/or actuate the liquid pump to introduce the supplementalliquid working fluid into the immersion chamber from the liquid buffertank. By only opening the liquid valve and/or actuating the liquid pumpafter the pressure has dropped, the supplemental liquid working fluidwill not experience the elevated internal pressure of the immersionchamber applying a force to the supplemental liquid working fluid thatresists the flow of the supplemental liquid working fluid into theimmersion chamber from the liquid buffer tank.

In some embodiments, in addition to the environmental sensor(s)positioned in or on the immersion tank, an immersion cooling systemincludes one or more flow sensors positioned in or on the vapor conduitand/or the liquid conduit. The flow sensors can measure the rate and/ortotal amount of vapor working fluid and/or liquid working fluid thatmoves out of and/or into the immersion chamber. For example, a flow rateof the vapor working fluid through the vapor conduit may be converted toa flow rate of the liquid working fluid through the liquid conduit basedon a relative density of the vapor phase to the liquid phase of theworking fluid to ensure the mass of working fluid in the immersionchamber remains substantially constant as vapor working fluid is ventedand supplemental liquid working fluid is introduced.

Optionally, the method includes condensing at least some of the ventedportion of the vapor working fluid in the vapor buffer tank to acondensate working fluid and returning the condensate working fluid tothe liquid buffer tank. In some embodiments, the vapor buffer tank mayinclude a condenser or other cooling surface to assist condensing thevapor working fluid. In some embodiments, at least some of the vaporworking fluid will condense in the vapor buffer tank in the absence ofheat-generating components.

In some embodiments, a vapor buffer tank and/or liquid buffer tank areconnected to a plurality of sealed IT modules. An immersion coolingsystem can include a plurality of sealed IT Modules connected inparallel with a vapor buffer tank and/or liquid buffer tank. In someembodiments, each of the parallel IT Modules has a vapor valve and/orvapor pump positioned in or on a vapor conduit to selectively connectthe IT Module to a vapor common conduit that combines vapor workingfluid from more than one IT Module. In some embodiments, each of theparallel IT Modules has a dedicated vapor conduit that connects theindividual IT Module to the vapor buffer tank.

In some embodiments, each of the parallel IT Modules has a liquid valveand/or liquid pump positioned in or on a liquid conduit to selectivelyconnect the IT Module to a liquid common conduit that providessupplemental liquid working fluid to more than one IT Module. In someembodiments, each of the parallel IT Modules has a dedicated liquidconduit that connects the individual IT Module to the liquid buffertank.

In the event of a failure of any of the condensers in each of the ITModules, the immersion cooling system can vent vapor working fluid fromthe IT Module experiencing the failure to the vapor buffer tank. Theimmersion cooling system can then direct supplemental working fluid fromthe shared liquid buffer tank to the IT Module.

In at least some embodiments of the present disclosure, an immersioncooling system can delay overheating or over-pressurization of theheat-generating components (such as computing components) in theimmersion chamber by venting vapor working fluid and introducingsupplemental liquid working fluid. By delaying the overheating orover-pressurization, the immersion cooling system can providetechnicians with additional time to arrive at and service the IT Modulebefore damage to the heat-generating components can occur.

The present disclosure relates to systems and methods for coolingheat-generating components of a computer or computing device accordingto at least the examples provided in the sections below:

(A1) In some embodiments, a thermal management system for coolingelectronic devices includes an immersion cooling system, a vapor buffertank, and a liquid buffer tank. The immersion cooling system includes animmersion tank, a working fluid, and a condenser. The immersion tankdefines an immersion chamber. The working fluid is positioned in theimmersion chamber, with a liquid portion of the working fluid definingan immersion bath in the immersion chamber and a vapor portion of theworking fluid defining a headspace above the immersion bath in theimmersion chamber. The condenser is positioned in fluid communicationwith the headspace to condense the vapor portion of the working fluid tothe liquid portion of the working fluid. The immersion cooling system isin fluid communication with the vapor buffer tank and the liquid buffertank. The vapor buffer tank is in fluid communication with the headspaceof the immersion chamber, and a vapor valve is positioned between thevapor buffer tank and the headspace to selectively allow fluidcommunication between the vapor buffer tank and the headspace. Theliquid buffer tank is in fluid communication with the immersion chamber,and a liquid valve is positioned between the liquid buffer tank and theimmersion chamber to selectively allow fluid communication between theliquid buffer tank and the immersion chamber.

[A2] In some embodiments, the thermal management system described in[A1] further includes a vapor valve controller in electricalcommunication with the vapor valve and at least one sensor. The vaporvalve controller adjusts a state of the vapor valve based at leastpartially on measurements from the at least one sensor.

[A3] In some embodiments, the sensor described in [A2] is a pressuresensor.

[A4] In some embodiments, the thermal management system described in anyof [A1]-[A3] further includes a liquid valve controller in electricalcommunication with the liquid valve and at least one sensor. The liquidvalve controller adjusts a state of the liquid valve based at leastpartially on measurements from the at least one sensor.

[A5] In some embodiments, the sensor described in [A4] is a liquid levelsensor.

[A6] In some embodiments, the thermal management system described in anyof [A1]-[A5] further includes a secondary condenser in fluidcommunication with the vapor buffer tank, which condenses vapor workingfluid in the vapor buffer tank to liquid working fluid.

[A7] In some embodiments, the thermal management system described in anyof [A1]-[A6] further includes a return conduit connecting the vaporbuffer tank to the liquid buffer tank. The return conduit returnscondensed liquid working fluid from the vapor buffer tank to the liquidbuffer tank.

[A8] In some embodiments, the thermal management system described in anyof [A1]-[A7] further includes a vapor pump positioned in the vaporconduit to urge vapor working fluid into the vapor buffer tank.

[A9] In some embodiments, the thermal management system described in anyof [A1]-[A8] further includes a liquid pump positioned in the liquidconduit to urge liquid working fluid into the immersion chamber.

[A10] In some embodiments, the thermal management system described inany of [A1]-[A9] further includes at least one flow rate sensorconfigured to measure mass of working fluid into or out of the immersionchamber.

[B1] In some embodiments, a thermal management system for coolingelectronic devices includes a first immersion cooling system, a secondimmersion cooling system, a vapor buffer tank, and a liquid buffer tank.Each immersion cooling system includes an immersion tank, a workingfluid, and a condenser. The immersion tank defines an immersion chamber.The working fluid is positioned in the immersion chamber, with a liquidportion of the working fluid defining an immersion bath in the immersionchamber and a vapor portion of the working fluid defining a headspaceabove the immersion bath in the immersion chamber. The condenser ispositioned in fluid communication with the headspace to condense thevapor portion of the working fluid to the liquid portion of the workingfluid. The immersion cooling system is in fluid communication with thevapor buffer tank and the liquid buffer tank. The vapor buffer tank isin fluid communication with the headspace of the immersion chamber ofthe first immersion cooling system, and a first vapor valve ispositioned between the vapor buffer tank and the headspace toselectively allow fluid communication between the vapor buffer tank andthe headspace. The vapor buffer tank is in fluid communication with theheadspace of the immersion chamber of the second immersion coolingsystem, and a second vapor valve is positioned between the vapor buffertank and the headspace to selectively allow fluid communication betweenthe vapor buffer tank and the headspace. The liquid buffer tank is influid communication with the immersion chamber of the first immersioncooling system, and a first liquid valve is positioned between theliquid buffer tank and the immersion chamber to selectively allow fluidcommunication between the liquid buffer tank and the immersion chamber.The liquid buffer tank is in fluid communication with the immersionchamber of the second immersion cooling system, and a second liquidvalve is positioned between the liquid buffer tank and the immersionchamber to selectively allow fluid communication between the liquidbuffer tank and the immersion chamber.

[B2] In some embodiments, wherein the first immersion chamber and secondimmersion chamber described in [B1] are in fluid communication with thevapor buffer tank via a vapor common conduit.

[B3] In some embodiments, wherein the first immersion chamber and secondimmersion chamber described in [B1] or [B3] are in fluid communicationwith the liquid buffer tank via a liquid common conduit.

[C1] In some embodiments, a method of thermal management includesreceiving heat from at least one heat-generating component with a liquidworking fluid in an immersion chamber; measuring temperature and/orpressure in the immersion chamber; upon the temperature and/or pressureexceeding a threshold value, venting a portion of a vapor working fluidfrom the immersion chamber to a vapor buffer tank.

[C2] In some embodiments, the method described in [C1] further includesurging supplemental liquid working fluid into the immersion chamber froma liquid buffer tank.

[C3] In some embodiments, measuring temperature and/or pressure in theimmersion chamber as described in [C1] or [C2] further comprisesmeasuring a pressure in the immersion chamber after venting the vaporworking fluid. The method then includes urging supplemental liquidworking fluid into the immersion chamber from a liquid buffer tank whenthe pressure falls below a fill threshold value.

[C4] In some embodiments, the method described in [C1] further includesmeasuring a liquid working fluid level and, when the liquid workingfluid level falls below a liquid level threshold value, urgingsupplemental liquid working fluid into the immersion chamber from aliquid buffer tank.

[C5] In some embodiments, the method described in [C1] further includes,after venting the portion of the vapor working fluid to the vapor buffertank, urging supplemental liquid working fluid into the immersionchamber from a liquid buffer tank after a predetermine time period.

[C6] In some embodiments, the method described in any of [C1]-[C5]further includes condensing the portion of the vapor working fluid inthe vapor buffer tank to a condensate working fluid; and returning thecondensate working fluid to a liquid buffer tank.

[C7] In some embodiments, the immersion chamber described in [C1]-[C6]is hermetically sealed.

The articles “a,” “an,” and “the” are intended to mean that there areone or more of the elements in the preceding descriptions. The terms“comprising,” “including,” and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements. Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features. For example, anyelement described in relation to an embodiment herein may be combinablewith any element of any other embodiment described herein. Numbers,percentages, ratios, or other values stated herein are intended toinclude that value, and also other values that are “about” or“approximately” the stated value, as would be appreciated by one ofordinary skill in the art encompassed by embodiments of the presentdisclosure. A stated value should therefore be interpreted broadlyenough to encompass values that are at least close enough to the statedvalue to perform a desired function or achieve a desired result. Thestated values include at least the variation to be expected in asuitable manufacturing or production process, and may include valuesthat are within 5%, within 1%, within 0.1%, or within 0.01% of a statedvalue.

A person having ordinary skill in the art should realize in view of thepresent disclosure that equivalent constructions do not depart from thespirit and scope of the present disclosure, and that various changes,substitutions, and alterations may be made to embodiments disclosedherein without departing from the spirit and scope of the presentdisclosure. Equivalent constructions, including functional“means-plus-function” clauses are intended to cover the structuresdescribed herein as performing the recited function, including bothstructural equivalents that operate in the same manner, and equivalentstructures that provide the same function. It is the express intentionof the applicant not to invoke means-plus-function or other functionalclaiming for any claim except for those in which the words ‘means for’appear together with an associated function. Each addition, deletion,and modification to the embodiments that falls within the meaning andscope of the claims is to be embraced by the claims.

It should be understood that any directions or reference frames in thepreceding description are merely relative directions or movements. Forexample, any references to “front” and “back” or “top” and “bottom” or“left” and “right” are merely descriptive of the relative position ormovement of the related elements.

The present disclosure may be embodied in other specific forms withoutdeparting from its spirit or characteristics. The described embodimentsare to be considered as illustrative and not restrictive. The scope ofthe disclosure is, therefore, indicated by the appended claims ratherthan by the foregoing description. Changes that come within the meaningand range of equivalency of the claims are to be embraced within theirscope.

What is claimed is:
 1. A thermal management system for coolingelectronic devices, the thermal management system comprising: animmersion cooling system including: an immersion tank defining animmersion chamber, a working fluid positioned in the immersion chamber,a liquid portion of the working fluid defining an immersion bath in theimmersion chamber and a vapor portion of the working fluid defining aheadspace above the immersion bath in the immersion chamber, and acondenser positioned in fluid communication with the headspace tocondense the vapor portion of the working fluid to the liquid portion ofthe working fluid; a vapor buffer tank in fluid communication with theheadspace of the immersion chamber; a vapor valve positioned between thevapor buffer tank and the headspace and configured to selectively allowfluid communication between the vapor buffer tank and the headspace; aliquid buffer tank in fluid communication with the immersion chamber;and a liquid valve positioned between the liquid buffer tank and theimmersion chamber and configured to selectively allow fluidcommunication between the liquid buffer tank and the immersion chamber.2. The thermal management system of claim 1, further comprising a vaporvalve controller and at least one sensor, the vapor valve controllerconfigured to adjust a state of the vapor valve based at least partiallyon measurements from the at least one sensor.
 3. The thermal managementsystem of claim 2, wherein the at least one sensor is a pressure sensor.4. The thermal management system of claim 1, further comprising a liquidvalve controller configured to adjust a state of the liquid valve basedat least partially on measurements from the at least one sensor.
 5. Thethermal management system of claim 4, wherein the at least one sensor isa liquid level sensor.
 6. The thermal management system of claim 1,further comprising a secondary condenser in fluid communication with thevapor buffer tank and configured to condense vapor working fluid in thevapor buffer tank to liquid working fluid.
 7. The thermal managementsystem of claim 1, further comprising a return conduit connecting thevapor buffer tank to the liquid buffer tank, the return conduitconfigured to return condensed liquid working fluid from the vaporbuffer tank to the liquid buffer tank.
 8. The thermal management systemof claim 1, further comprising a vapor pump positioned in the vaporconduit to pump vapor working fluid into the vapor buffer tank.
 9. Thethermal management system of claim 1, further comprising a liquid pumppositioned in the liquid conduit to pump liquid working fluid into theimmersion chamber.
 10. The thermal management system of claim 1, furthercomprising at least one flow rate sensor configured to measure mass ofworking fluid into or out of the immersion chamber.
 11. A thermalmanagement system for cooling electronic devices, the thermal managementsystem comprising: a first information technology module including: afirst immersion tank defining a first immersion chamber, working fluidpositioned in the first immersion chamber, a liquid portion of theworking fluid defining a first immersion bath in the first immersionchamber and a vapor portion of the working fluid defining a firstheadspace above the first immersion bath in the first immersion chamber,and a first condenser positioned in fluid communication with the firstheadspace to condense the vapor portion of the working fluid to theliquid portion of the working fluid; a second information technologymodule including: a second immersion tank defining a second immersionchamber, a working fluid positioned in the second immersion chamber, aliquid portion of the working fluid defining a second immersion bath inthe second immersion chamber and a vapor portion of the working fluiddefining a headspace above the immersion bath in the immersion chamber,and a condenser positioned in fluid communication with the headspace tocondense the vapor portion of the working fluid to the liquid portion ofthe working fluid; a vapor buffer tank in fluid communication with thefirst headspace and second headspace; a first vapor valve positionedbetween the vapor buffer tank and the first headspace and configured toselectively allow fluid communication between the vapor buffer tank andthe first headspace; a second vapor valve positioned between the vaporbuffer tank and the second headspace and configured to selectively allowfluid communication between the vapor buffer tank and the secondheadspace; a liquid buffer tank in fluid communication with the firstimmersion chamber and the second immersion chamber; a first liquid valvepositioned between the liquid buffer tank and the first immersionchamber and configured to selectively allow fluid communication betweenthe liquid buffer tank and the first immersion chamber; and a secondliquid valve positioned between the liquid buffer tank and the secondimmersion chamber and configured to selectively allow fluidcommunication between the liquid buffer tank and the second immersionchamber.
 12. The thermal management system of claim 11, wherein thefirst immersion chamber and the second immersion chamber are in fluidcommunication with the vapor buffer tank via a vapor common conduit. 13.The thermal management system of claim 11, wherein the first immersionchamber and second immersion chamber are in fluid communication with theliquid buffer tank via a liquid common conduit.
 14. A method of thermalmanagement of heat-generating components, the method comprising:receiving heat from at least one heat-generating component with a liquidworking fluid in an immersion chamber; measuring one or more oftemperature or pressure in the immersion chamber; upon one or more ofthe temperature or pressure exceeding a threshold value, venting aportion of a vapor working fluid from the immersion chamber to a vaporbuffer tank.
 15. The method of claim 14, further comprising: pumpingsupplemental liquid working fluid into the immersion chamber from aliquid buffer tank.
 16. The method of claim 14, wherein measuring one ormore of temperature or pressure in the immersion chamber furthercomprises measuring a pressure in the immersion chamber after ventingthe vapor working fluid, and pumping supplemental liquid working fluidinto the immersion chamber from a liquid buffer tank when the pressurefalls below a fill threshold value.
 17. The method of claim 14, furthercomprising: measuring a liquid working fluid level, and when the liquidworking fluid level falls below a liquid level threshold value, pumpingsupplemental liquid working fluid into the immersion chamber from aliquid buffer tank.
 18. The method of claim 14, further comprising:after venting the portion of the vapor working fluid to the vapor buffertank, pumping supplemental liquid working fluid into the immersionchamber from a liquid buffer tank after a predetermined time period. 19.The method of claim 14, further comprising condensing the portion of thevapor working fluid in the vapor buffer tank to a condensate workingfluid; and returning the condensate working fluid to a liquid buffertank.
 20. The method of claim 14, wherein the immersion chamber ishermetically sealed.